Recent data from the 1999-2000 National Health and Nutrition Examination Survey indicate a continuation of the trend for increasing prevalence of obesity in the US population. These trends reflect a persistent positive energy balance in the US population. Ecologic data suggest that energy intakes in the past three decades have increased without a concomitant increase in energy expenditure. Multiple factors are probably responsible for the increase in energy intake, but are poorly understood. Bio-behavioral factors such as consumption of foods prepared away from home and large portion sizes are currently receiving attention as possible contributors to increasing energy intake. However, an expanding food supply, aggressive food marketing, and changes in work and leisure behaviors over the past three decades may be expected to influence several other food related behaviors that may relate to energy intake and thus affect energy balance. These food consumption behaviors include dietary variety and energy density; frequency of eating episodes/snacking; breakfast, and evening/night eating patterns. Surprisingly little, however, is known about trends in these food consumption behaviors. Therefore, the overall objective of the proposed study is to examine trends in patterns of food consumption (as reflected in dietary variety and energy density, frequency of eating episodes/snacking, breakfast, and evening/night eating behaviors) from 1971-2002, to understand their potential contribution to energy intake and increasing adiposity of the US population. Accordingly, we will test these hypotheses: 1) patterns of food consumption (dietary variety and energy density, frequency of eating episodes/snacking, and breakfast, evening/night eating behaviors) are independent predictors of self-reported dietary energy intake, indices of adiposity, and biomarkers in the adult US population, 2) the patterns of food consumption have changed from 1971 to 2002, and 3) the secular changes in patterns of food consumption from 1971-2002 are associated with secular changes in energy intake and indices of adiposity from 1971-2002. We will use nationally representative data from the National Health and Nutrition Examination Surveys I (1971-74), II (1976-1980), III (1988-1994), and 1999-2002, to examine these hypotheses. An examination of changing patterns of food consumption can help in understanding the correlates of increasing energy intake and permit designing and targeting of suitable interventions by both the public and the private sectors.